The Real need for per hour LGal output

Hi there,

Im planning on putting a filter with 800 L per hour ( 211 gal ) on a 200 L tank ( 55 gal )

But i really wanted the water circulation to a _minimum_ my question is, what is really _the real_ need for pummping xxx L or gal per hour ? From what i read people even advocate a tank can live without filtration whatsoever, it sure makes sense in some points, the bacteria is mainly in the gravel and the plants, the plants help out the process of eliminating amonia a lot. What is the real need ?

It's not going to be a heavily stocked tank. I really want the least circulation possible, i have at this time one 300 L per hour in a 55 L tank and there's way to much water circulation even the the water output directed to the best place.

Of course i wanto to be sure as i do not want to put the fish at risk. But the fact that plants, and the bacteria in the gravel look like the main biological filtration, i'm left wondering if these ratios of x Lgal per hour are really worth anything ( as i can see it only helps in the mechanical filtration )

Thanks for any enlighment in advance.

There are schools of thought that advocate no need for filtration. Underground, canister or hang on, provided an alternative, such as plants are introduced into the environment in sufficient quantity to handle the ammonia load of the fish, food etc. Filtration for me provides a means to pull particulates from the water column, a way to introduce CO2 and way to provide water movement that circulates nutrients to the plants. Besides I must need one. If I didn't they wouldn't have so many on the market - right?

I have seen a couple of perfectly balanced perfectly beautiful planted tanks of Japanese influence that have no augmentation other than lights. but I understand its quite a balancing act and one I know I'm not up to.

Im just thinking of putting a smaller o 300 L instead of a 800 L or more. Exactly for that, to circulate the water, and remove some particulates ( and why not provide some bacterial filtration ) i'm not quite ready to remove a filter alltogether, but i want to downsize the usual ratio of 3 to 4 times the tank's size, it produces way to much current. That being, im wondering : will there be a problem, im afraid to risk anything since the current ratios are for 3 to 5 times over the size of the tank, is it an actual necessity ? Or will the plants and the bacteria in the substrate make up for it ? ( i've read the bacteria in the filter is just 15% of all present in the tank ) Is it actually necessary that the whole water in the tank goes through the filter 3 to 5 times in an hour ?

I agree with the other poster too, i think the area is really what is important, that's why im wondering what's ( if any ) the value of pumping the tanks contents 3 to 5 times per hour and if that's really needed ...

Yeah (...) right ...

The 3-4 tank volume turnover rate was basically established back in the 'good old days' when filtration wasn't all that effective. A turnover of at least twice the volume in an hour is enough to ensure adequate aeration throughout the tank, as well as an even distribution of nutrients _and_ wastes. After all, what good are nitrifying bacteria if they can only affect the water in immediate contact with them?

As to the _speed_ of your current, I have to ask just what's in your tank that gives the impression everything's being 'blown around' (my own phrasing). A typical, slow- moving river eases along at about walking speed, or 3 miles per hour. That's about 4-1/2 feet per second, or in perspective, the length of your tank *every second*...

I thought the accepted turnover rate for an average setup, for modern filters, was once/hour.

I think there are good reasons to use a power filter. Think about all the gunk that you see on the media when you clean it out, would you want that in your tank? I don't know any figures, but you say that only 15% of the tanks bacteria are in the filter. I think that these bacteria would be more effecive though as they are in an area of higher turnover, so the filter helps for fast breakdown of organic waste.

I don't believe 15%. You could possibly come up with a sufficiently bad filter design that you achieved that, but not in a reasonable setup.

However, for minimum water-flow in the tank, use an undergravel with a bubble-lift. Practically no discernible current.

regards, Ian SMith

I think foremost the real need these high-gph formulas are trying to meet is to ensure enough circulation for good aeration for fish (not necessarily necessary in a plant tank or one with a bubbler or one that isn't overstocked) and to provide enough pull at the intake for good mechanical filtration (haven't seen a tank yet that couldn't benefit from good mechanical filtration.) Also, as Nestor said, wastes and nutrients do need to be circulated. The secondary reason I often see is that a lot of the smaller filters, with their smaller biological media volumes, need the increased gph to filter the same bio load that slow filters with larger bio media volumes do.

For example, the relatively-small Aquaclears usually recommend about 6x/hr, but the largest Eheim canisters (2260 for up to 400 gallon tanks) filter at less than 1x/hr. However, this model can hold up to 5 US gallons of bio media! So, if you want a slow flow through your tank and don't mind the lesser mechanical filtration, you can do fine with a slow filter on a plant tank, as long as you make sure you have a sufficiently large bio media volume that will support the water volume/bio load you have (load = any waste the plants and internal bacteria don't get to first.)

In short, the answer to whether 200 gph or less is enough for a 55 gal tank depends entirely on what brand and model of filter you will be usin, what you will be using for media, and what your tank's bio load is. If you're talking about an Eheim or similar, you're probably set, but if you're talking about an old-style Whisper power filter or similar, you could be setting yourself up for trouble.

In a later post:

I've seen one or two people throw this figure out on these groups, but so far, despite requesting it, I have not been presented with one bit of real research to back this claim up. If you read the claimed surface area sizes for some of the specialized ceramic or sintered glass bio mediums out there, sometimes as little as one liter of the stuff can have the surface area of a tennis court, or more! Try to convince me that in a 125 gallon tank, you'll have more surface area on the glass, _top_ layer of gravel, and plant surfaces to make up 85% more surface area than 5 or 6 liters of the high-surface area media I mentioned above (I'm thinking of an Eheim Pro 2228 and 5-6 liters of Ehfisubstrat as my illustration.)

Frankly, I will continue to think that this figure that someone introduced to back up some point they were trying to make is absolute, complete bullshit, until I am presented with some legitimate research by a professional, independant source that backs up their claim. I don't take, 'Well, that's what I heard,' as proof that this figure is true. Until _we_ are presented with legitimate proof, I encourage other people not to propagate this claim, before it takes on a life of its own, at which time no amount of research would be able to refute it if it isn't true. Such is the power of Old Wives' Tales, so don't let it become one.

See ya,

Kristen

BTW, try using a few periods in your future postings. It makes it much easier for people to read if the whole thing isn't one big, run-on sentence.

I am doing well with an eheim 2224 on a 200 l tank. The tank is planted and quite heavily stocked with fish. After running that filter about one year, i noticed a significant decrease in turnover. The tubes and filter-pump were clogged.I measured a turnover of just 150 l/h, which is about 1/6 of the pump rate with that filter. The fish and plants were doing fine, even better than with the normal output.

In normal (cleaned) operation, that filter takes about 350-450 l/h, which is about 1,5 to 2,0 times the tank size. That is enough for planted tank, esp. if you inject CO2, as i do.

As Kirsten puts it: The most important factor to biological filtration is filter size and proper oxygen in the filter material.

One thing you have to watch: If filtration rate goes down, there sometimes is a O2-leak, if the plants do not grow properly or if the tank becomes muddy.

So it is no problem to cut down filtration rates. But you have to watch the O2 level.

I'd accept coherent logical argument from an ameteur, but otherwise I agree with Kristen. 15% is just not credible, even with a spectacularly poor media.

The tank Amos resides in is 360 x 910 (internally) with 310 mm deep water.

That's a surface area 2 x (360 + 910) x 310 + 360 x 910 = 787400 + 327600 = 1115000 square milimeters

The filter on this tank is a Eheim pro, with filter container internal dimensions 198 square by 215 deep.

That's a surface area 4 x 198 x 215 + 2 x 198 x 198 = 170280 + 78408 = 248688

So, my EMPTY filter has a surface area ready for biological colonisation that is 22% of that available in the tank.

Of course, the tank has some decor, and some gravel (but the water doesn't pass through the gravel, so only the top layer will do any good) so maybe the surface area in the tank is twice the value I estimated. Let's see, twice 1115000 is 2230000, and 15% of that is 334500. The filter already has 248688, leaving me to find an extra 85812 sq mm. However, the filter has some associated plumbing, in 12mm pipe, which has 37.68 mm internal circumference, and there's about 2.5m of it, which is 94200 sq mm. Well I never! I've got more than 15% of the tank surface area in the filter and plumbing BEFORE I add EVEN ONE PIECE of filter media.

Maybe if you've got a small filter, and you accidentaly forget to add any media, you'll achieve this 15%. In any other circumstance, the figure is not believable.

regards, Ian SMith

I can't resist.

The question of what type of filter and how much filtration has always bothered me.

In the lake near my house there is no filtration.

there is air exchange at the surface and live plants to add O2 to the water, and a small stream for inflow and a small stream for outflow.

During the rainy seasons and spring runoff there is a large amount of relatively fresh rain water (a little sulfer based acid rain as well) but the lake is very alkaline.

The lake does very will as a balanced system because of its large size and relatively low stocking level.

back to filtration and aeration AND WATER CIRCULATION - these help increase the amount of livestock you can safely have in your tank by 1. filtration across a biological filter helps change ammonia / nitrites / nitrates to less harmfil forms 2. circulation helps increas gas exchange (O2 & CO2) at the surface.

BOTH ARE NEEDED

Circulation can be done by an air stone setting up currents in your water Circulation can be done by a air pump / filter setting up currents in your water Circulation can be done by a filter (like an aquaclear) setting up currents in your water

Air exchange can be helped by A simple powerhead can be used to help increase surface water circulation without a filter. An external filter that gives lots of air / water contact. A fountain (like in a fish pond) can be used.

Removal of posionous wastes can be done by Filtration Water changes Live plants - The Best Chemical methods (Not recommended) like AmmoLock Scavengers that reduce the amount of leftover food.

******* If you don't have test kits there are some ways to see if your water is bad.

Algee means you have too many nitrates (and other plant nutrients) for your system Fish going to the surface to gulp air means there is not enough oxygen (air exchange)

Wow, talk about ignorance. Of course there is filtration in lake and rivers. What do you think the slim on the rock is ? fish snot ? What do you think the swampy parts in bays do to the water, all along the edge of the lake and isle where plants grow. how about the underground streams. Geez how stupid can you be.

I don't know where you live, but around here (quebec canada) we also have lakes that are fed by multiple rivers and have even larger river for out flow. At the other end of the scale we have some lakes that are only fed from under ground and overflows out in a stream.

Generalizing again, the world does not stop at the edge of your pack yard. Some lake are naturally acidic, why do you thing some fish are strongly recommended for acidic water. Ooops there goes another gear...

of course they are, they are also needed in nature. Very few still lake are large enough to sustain live for any length of time. Look at any artificial lake with no filtration or current, the fish eventually die. A golf course near here learned that. The lake died after 4 years high level of nitrates and ammonia where found in the water. You forgot to put air stone here too. Air exchange and circulation do go hand in hand. One does not imply the other though.

The only thing that will take *out* mater here is water changes and chemical methods. I do not recommend chemical filtration either. All the other transform the matter and do not remove it. Plants are the best way to get ride of nitrogens because they will use them during photosynthesis and give of oxygen. Filtration one transform matter into a different state organic -> ammonia -> nitrite -> nitrate but the matter is still there.

algae can also grow is a phosphate rich environment even if there is no nitrates.

Or a gill disease or poisoning...